
\begin{tabular}{rrrrrrr}
\toprule
\multicolumn{1}{c}{ } & \multicolumn{3}{c}{BRS} & \multicolumn{3}{c}{QCA} \\
\cmidrule(l{3pt}r{3pt}){2-4} \cmidrule(l{3pt}r{3pt}){5-7}
N & Num. Rules & Rule Len. & Accuracy & Num. Rules & Rule Len. & Accuracy\\
\midrule
25 & 1.39 & 2.02 & 0.61 & 3.35 & 2.94 & 0.60\\
100 & 1.29 & 2.31 & 0.69 & 4.18 & 3.96 & 0.65\\
250 & 1.65 & 2.42 & 0.73 & 3.82 & 3.80 & 0.69\\
500 & 1.86 & 2.46 & 0.74 & 3.53 & 3.58 & 0.71\\
750 & 1.97 & 2.49 & 0.75 & 3.63 & 3.45 & 0.72\\
\addlinespace
1000 & 1.98 & 2.49 & 0.75 & 3.30 & 3.37 & 0.72\\
\bottomrule
\end{tabular}
